diff --git a/paket.dependencies b/paket.dependencies
index f0eeb9edb..b7b558e71 100644
--- a/paket.dependencies
+++ b/paket.dependencies
@@ -13,7 +13,7 @@ lowest_matching: true
 
 nuget BenchmarkDotNet 0.13.5
 nuget Fantomas.Client >= 0.9
-nuget FSharp.Compiler.Service >= 43.7.300
+nuget FSharp.Compiler.Service >= 43.7.400
 nuget Ionide.ProjInfo >= 0.61.3
 nuget Ionide.ProjInfo.FCS >= 0.61.3
 nuget Ionide.ProjInfo.ProjectSystem >= 0.61.3
diff --git a/paket.lock b/paket.lock
index de2df54d3..6e0cbe620 100644
--- a/paket.lock
+++ b/paket.lock
@@ -59,14 +59,14 @@ NUGET
       FSharp.Compiler.Service (>= 41.0.1) - restriction: || (== net6.0) (== net7.0) (&& (== netstandard2.0) (>= net5.0)) (&& (== netstandard2.1) (>= net5.0))
       FSharp.Core (>= 6.0.1) - restriction: || (== net6.0) (== net7.0) (&& (== netstandard2.0) (>= net5.0)) (&& (== netstandard2.1) (>= net5.0))
       McMaster.NETCore.Plugins (>= 1.4) - restriction: || (== net6.0) (== net7.0) (&& (== netstandard2.0) (>= net5.0)) (&& (== netstandard2.1) (>= net5.0))
-    FSharp.Compiler.Service (43.7.300)
-      FSharp.Core (7.0.300)
+    FSharp.Compiler.Service (43.7.400)
+      FSharp.Core (7.0.400)
       System.Buffers (>= 4.5.1)
-      System.Collections.Immutable (>= 6.0)
-      System.Diagnostics.DiagnosticSource (>= 6.0)
+      System.Collections.Immutable (>= 7.0)
+      System.Diagnostics.DiagnosticSource (>= 7.0.2)
       System.Memory (>= 4.5.5)
       System.Reflection.Emit (>= 4.7)
-      System.Reflection.Metadata (>= 6.0.1)
+      System.Reflection.Metadata (>= 7.0)
       System.Runtime.CompilerServices.Unsafe (>= 6.0)
     FSharp.Control.AsyncSeq (3.2.1)
       FSharp.Core (>= 4.7.2)
@@ -74,7 +74,7 @@ NUGET
     FSharp.Control.Reactive (5.0.5) - restriction: || (== net6.0) (== net7.0) (&& (== netstandard2.0) (>= net6.0)) (&& (== netstandard2.1) (>= net6.0))
       FSharp.Core (>= 4.7.2)
       System.Reactive (>= 5.0 < 6.0)
-    FSharp.Core (7.0.300)
+    FSharp.Core (7.0.400)
     FSharp.Data.Adaptive (1.2.13)
       FSharp.Core (>= 4.7)
       System.Reflection.Emit.Lightweight (>= 4.6)
@@ -395,9 +395,9 @@ NUGET
       System.Threading.Tasks.Dataflow (>= 6.0)
     System.Buffers (4.5.1)
     System.CodeDom (6.0) - copy_local: false
-    System.Collections.Immutable (6.0)
-      System.Memory (>= 4.5.4) - restriction: || (&& (== net6.0) (>= net461)) (&& (== net7.0) (>= net461)) (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
-      System.Runtime.CompilerServices.Unsafe (>= 6.0)
+    System.Collections.Immutable (7.0)
+      System.Memory (>= 4.5.5) - restriction: || (&& (== net6.0) (>= net462)) (&& (== net7.0) (>= net462)) (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
+      System.Runtime.CompilerServices.Unsafe (>= 6.0) - restriction: || (== net6.0) (&& (== net7.0) (>= net462)) (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
     System.CommandLine (2.0.0-beta4.22272.1)
       System.Memory (>= 4.5.4) - restriction: || (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
     System.ComponentModel.Annotations (5.0) - restriction: || (&& (== net6.0) (< netstandard2.1)) (&& (== net7.0) (< netstandard2.1)) (== netstandard2.0)
@@ -420,9 +420,9 @@ NUGET
     System.Configuration.ConfigurationManager (6.0)
       System.Security.Cryptography.ProtectedData (>= 6.0)
       System.Security.Permissions (>= 6.0)
-    System.Diagnostics.DiagnosticSource (6.0)
-      System.Memory (>= 4.5.4) - restriction: || (&& (== net6.0) (>= net461)) (&& (== net6.0) (< net5.0)) (&& (== net7.0) (>= net461)) (&& (== net7.0) (< net5.0)) (== netstandard2.0) (== netstandard2.1)
-      System.Runtime.CompilerServices.Unsafe (>= 6.0)
+    System.Diagnostics.DiagnosticSource (7.0.2)
+      System.Memory (>= 4.5.5) - restriction: || (&& (== net6.0) (>= net462)) (&& (== net7.0) (>= net462)) (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
+      System.Runtime.CompilerServices.Unsafe (>= 6.0) - restriction: || (== net6.0) (&& (== net7.0) (>= net462)) (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
     System.Drawing.Common (6.0) - copy_local: false, restriction: || (== net6.0) (== net7.0) (&& (== netstandard2.0) (>= netcoreapp3.1)) (&& (== netstandard2.1) (>= netcoreapp3.1))
       Microsoft.Win32.SystemEvents (>= 6.0) - restriction: || (== net6.0) (== net7.0) (&& (== netstandard2.0) (>= netcoreapp3.1)) (&& (== netstandard2.1) (>= netcoreapp3.1))
     System.Formats.Asn1 (6.0) - copy_local: false
@@ -445,8 +445,9 @@ NUGET
     System.Reflection.Emit.ILGeneration (4.7) - restriction: || (&& (== net7.0) (< netcoreapp2.0) (< netstandard2.1)) (&& (== net7.0) (< netstandard1.1)) (&& (== net7.0) (< netstandard2.0)) (&& (== net7.0) (>= uap10.1)) (== netstandard2.0) (&& (== netstandard2.1) (< netstandard1.1)) (&& (== netstandard2.1) (< netstandard2.0)) (&& (== netstandard2.1) (>= uap10.1))
     System.Reflection.Emit.Lightweight (4.7)
       System.Reflection.Emit.ILGeneration (>= 4.7) - restriction: || (&& (== net6.0) (< netcoreapp2.0) (< netstandard2.1)) (&& (== net6.0) (< netstandard2.0)) (&& (== net6.0) (< portable-net45+wp8)) (&& (== net6.0) (>= uap10.1)) (&& (== net7.0) (< netcoreapp2.0) (< netstandard2.1)) (&& (== net7.0) (< netstandard2.0)) (&& (== net7.0) (< portable-net45+wp8)) (&& (== net7.0) (>= uap10.1)) (== netstandard2.0) (&& (== netstandard2.1) (< netstandard2.0)) (&& (== netstandard2.1) (< portable-net45+wp8)) (&& (== netstandard2.1) (>= uap10.1))
-    System.Reflection.Metadata (6.0.1)
-      System.Collections.Immutable (>= 6.0)
+    System.Reflection.Metadata (7.0)
+      System.Collections.Immutable (>= 7.0)
+      System.Memory (>= 4.5.5) - restriction: || (&& (== net6.0) (>= net462)) (&& (== net7.0) (>= net462)) (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
     System.Resources.Extensions (6.0) - copy_local: false
       System.Memory (>= 4.5.4) - restriction: || (&& (== net6.0) (>= net461)) (&& (== net7.0) (>= net461)) (&& (== net7.0) (< net6.0)) (== netstandard2.0) (== netstandard2.1)
     System.Runtime.CompilerServices.Unsafe (6.0)
diff --git a/src/FsAutoComplete.Core/CompilerServiceInterface.fs b/src/FsAutoComplete.Core/CompilerServiceInterface.fs
index a167bbc14..fa62bc559 100644
--- a/src/FsAutoComplete.Core/CompilerServiceInterface.fs
+++ b/src/FsAutoComplete.Core/CompilerServiceInterface.fs
@@ -21,16 +21,17 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
   let checker =
     FSharpChecker.Create(
       projectCacheSize = 200,
-      keepAllBackgroundResolutions = true,
       keepAssemblyContents = hasAnalyzers,
+      keepAllBackgroundResolutions = true,
       suggestNamesForErrors = true,
-      enablePartialTypeChecking = not hasAnalyzers,
+      keepAllBackgroundSymbolUses = true,
       enableBackgroundItemKeyStoreAndSemanticClassification = true,
-      keepAllBackgroundSymbolUses = true
+      enablePartialTypeChecking = not hasAnalyzers,
+      parallelReferenceResolution = true,
+      captureIdentifiersWhenParsing = true,
+      useSyntaxTreeCache = true
     )
 
-
-
   let entityCache = EntityCache()
 
   // This is used to hold previous check results for autocompletion.
diff --git a/src/FsAutoComplete.Core/InlayHints.fs b/src/FsAutoComplete.Core/InlayHints.fs
index 724b4d9c8..0836a4dcf 100644
--- a/src/FsAutoComplete.Core/InlayHints.fs
+++ b/src/FsAutoComplete.Core/InlayHints.fs
@@ -31,7 +31,7 @@ and private defaultTraversePat visitor origPath pat =
   | SynPat.As(p1, p2, _)
   | SynPat.Or(p1, p2, _, _) -> [ p1; p2 ] |> List.tryPick (traversePat visitor path)
   | SynPat.Ands(ps, _)
-  | SynPat.Tuple(_, ps, _)
+  | SynPat.Tuple(_, ps, _, _)
   | SynPat.ArrayOrList(_, ps, _) -> ps |> List.tryPick (traversePat visitor path)
   | SynPat.Attrib(p, _, _) -> traversePat visitor path p
   | SynPat.LongIdent(argPats = args) ->
diff --git a/src/FsAutoComplete.Core/Lexer.fs b/src/FsAutoComplete.Core/Lexer.fs
index 387e63972..288991bd2 100644
--- a/src/FsAutoComplete.Core/Lexer.fs
+++ b/src/FsAutoComplete.Core/Lexer.fs
@@ -41,14 +41,36 @@ type private DraftToken =
 module Lexer =
   let logger = LogProvider.getLoggerByName "Lexer"
 
+  [<return:Struct>]
+  let (|Define|_|) (a: string) =
+    if a.StartsWith "--defin:" then
+      ValueSome(a.[9..])
+    else
+      ValueNone
+
+  [<return:Struct>]
+  let (|LangVersion|_|) (a: string) =
+    if a.StartsWith "--langversion:" then
+      ValueSome(a.[14..])
+    else
+      ValueNone
+
   /// Return all tokens of current line
   let tokenizeLine (args: string[]) lineStr =
-    let defines =
-      args
-      |> Seq.choose (fun s -> if s.StartsWith "--define:" then Some s.[9..] else None)
-      |> Seq.toList
+    let defines, langVersion =
+      ((ResizeArray(), None),  args)
+      ||> Array.fold (fun (defines, langVersion) arg ->
+          match arg with
+          | Define d ->
+            defines.Add(d)
+            defines, langVersion
+          | LangVersion v ->
+            defines, Some(v)
+          | _ ->
+            defines, langVersion
+      )
 
-    let sourceTokenizer = FSharpSourceTokenizer(defines, Some "/tmp.fsx")
+    let sourceTokenizer = FSharpSourceTokenizer(Seq.toList defines, Some "/tmp.fsx", langVersion)
     let lineTokenizer = sourceTokenizer.CreateLineTokenizer lineStr
 
     let rec loop lexState acc =
diff --git a/src/FsAutoComplete.Core/UnionPatternMatchCaseGenerator.fs b/src/FsAutoComplete.Core/UnionPatternMatchCaseGenerator.fs
index 08e9c81d1..b0f2f73c7 100644
--- a/src/FsAutoComplete.Core/UnionPatternMatchCaseGenerator.fs
+++ b/src/FsAutoComplete.Core/UnionPatternMatchCaseGenerator.fs
@@ -311,7 +311,7 @@ let getWrittenCases (patMatchExpr: PatternMatchExpr) =
     | SynPat.ListCons _
     | SynPat.FromParseError(_, _) -> false
 
-    | SynPat.Tuple(_, innerPatList, _) -> List.forall checkPattern innerPatList
+    | SynPat.Tuple(_, innerPatList, _, _) -> List.forall checkPattern innerPatList
 
     | SynPat.Record(recordInnerPatList, _) ->
       recordInnerPatList
diff --git a/src/FsAutoComplete.Core/UntypedAstUtils.fs b/src/FsAutoComplete.Core/UntypedAstUtils.fs
index 6d495c4ef..bf585807b 100644
--- a/src/FsAutoComplete.Core/UntypedAstUtils.fs
+++ b/src/FsAutoComplete.Core/UntypedAstUtils.fs
@@ -50,8 +50,7 @@ let (|AllAttrs|) (attrs: SynAttributes) =
 let (|AllSimplePats|) (pats: SynSimplePats) =
   let rec loop acc pat =
     match pat with
-    | SynSimplePats.SimplePats(pats, _) -> acc @ pats
-    | SynSimplePats.Typed(pats, _, _) -> loop acc pats
+    | SynSimplePats.SimplePats(pats, _, _) -> acc @ pats
 
   loop [] pats
 
@@ -122,7 +121,7 @@ let internal getRangesAtPosition input (r: Position) : Range list =
 
   and walkPat =
     function
-    | SynPat.Tuple(_, pats, r)
+    | SynPat.Tuple(_, pats, _, r)
     | SynPat.ArrayOrList(_, pats, r)
     | SynPat.Ands(pats, r) ->
       addIfInside r
@@ -243,6 +242,8 @@ let internal getRangesAtPosition input (r: Position) : Range list =
       addIfInside r
       walkType lhs
       walkType rhs
+    | SynType.FromParseError(r) ->
+      addIfInside r
 
   and walkClause (SynMatchClause(pat, e1, e2, r, _, _)) =
     addIfInside r
@@ -252,13 +253,9 @@ let internal getRangesAtPosition input (r: Position) : Range list =
 
   and walkSimplePats =
     function
-    | SynSimplePats.SimplePats(pats, r) ->
+    | SynSimplePats.SimplePats(pats, _, r) ->
       addIfInside r
       List.iter walkSimplePat pats
-    | SynSimplePats.Typed(pats, ty, r) ->
-      addIfInside r
-      walkSimplePats pats
-      walkType ty
 
   and walkInterpolatedStringPart =
     function